Media conglomerate Viacom has announced that it is to sue YouTube and Google for $1 billion (£518 million) over unauthorised use of programming online.
Viacom, whose brands include MTV, Nickelodeon and VH1, claims that YouTube's owner Google has carried out "massive copyright infringement".
Filing the suit at the US district court for the southern district of New York, the group is seeking $1 billion in damages as well as an injunction to prevent shows from being illegally shown.
Almost 160,000 unauthorised clips of programming have been loaded onto YouTube and viewed more than 1.5 billion times, Viacom claims.
"YouTube's strategy has been to avoid taking proactive Steps to curtail the infringement on its site," Viacom said in a statement.
"Their business model, which is based on building traffic and selling advertising off of unlicensed content, is clearly illegal and is in obvious conflict with copyright laws."
The lawsuit is the culmination of tensions between Viacom and Google, which have been escalating for the last few months over disputes about programming content online.
Last month Viacom demanded that more than 100,000 unauthorised clips be removed from YouTube after several months of talks between the companies broke down.